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  • Articles  (5,431)
  • Chemistry  (5,393)
  • 42.55  (37)
  • Compartment fires
  • Sound production
  • 2005-2009
  • 1980-1984  (5,431)
  • Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics  (5,430)
  • Architecture, Civil Engineering, Surveying  (196)
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  • Articles  (5,431)
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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Fire technology 20 (1984), S. 39-63 
    ISSN: 1572-8099
    Keywords: Compartment fires ; fire models ; fire plumes ; room fires ; sprinkler systems
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying
    Notes: Abstract Methods are developed to determine axial gas flow conditions within a weakly buoyant plume that passes from an ambient quiescent environment, in which the plume originates, to an upper layer at elevated temperatures. The methods are appropriate for inclusion in two-layer analysis of enclosure fire. In particular, they are first steps in developing a prediction of actuation time for thermally activated automatic sprinklers exposed to an enclosure fire. Results obtained with various methods are compared with measurements in a 1.22 m diameter cylindrical enclosure.
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  • 2
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    Applied physics 22 (1980), S. 175-184 
    ISSN: 1432-0630
    Keywords: 42.55
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract The problem of output-coupling optimization of a transversely or longitudinally pumped dye laser is treated in terms of a rate equation approach under steady state considerations. The theoretical study considers the spatial variation of the gain distribution and such typical features of a dye laser as reabsorption, triplet effects and excited state absorption. Numerical results obtained with realistic values of typical laser parameters (cross-sections for stimulated emission and reabsorption, number density of active molecules etc.) indicate that a higher degree of output coupling and consequently higher output powers are feasible upon a complete consideration of the spatial gain distribution
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  • 3
    ISSN: 1432-0630
    Keywords: 42.55 ; 42.80 ; 33
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract As an outcome of a systematic study of excitation kinetics and fluorescence spectra concerning theD′(3π2u )→A′(3π2g ) transitions in homonuclear diatomic halogens and corresponding transitions in interhalogen molecules [1], this paper describes, for the first time, TEA laser action in the three halogen monofluorides ClF, BrF, and IF. Output energies in the mJ range were demonstrated in a fast TEA discharge arrangement at the wavelengths of 284.4, 354.5, and 490.8 nm for ClF, BrF, and IF, respectively. The results suggest parameter scalability and wavelength tunability.
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  • 4
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    Applied physics 24 (1981), S. 13-20 
    ISSN: 1432-0630
    Keywords: 42.55 ; 78.60
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Simultaneous laser operation at the wavelengths of λ1=637 and λ2=717 in Pr0.5La0.5P5O14 single crystals was observed. The crystals were excited by nanosecond publses from a Coumarin 2 dye laser (λ=450 nm). Laser emissions and their interdependence were studied both in crystals without an external resonator and in crystals placed within a plane parallel resonator. The energetic, time and frequency characteristics for both laser actions were examined. The effect of bifrequential emission was also found in crystals of different ratios of Pr and La ions concentration and in pure praseodymium pentaphosphate.
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  • 5
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    Applied physics 21 (1980), S. 25-28 
    ISSN: 1432-0630
    Keywords: 35 ; 42.55
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract He−Zn and He−ZnCl2 hollow cathode discharges were compared. The metal vapour concentration necessary for laser operation can be achieved at a lower temperature for the molecular substance. On the other hand, the efficiency decreases because part of the He ions necessary for the selective excitation of the upper laser level of the metal ion are lost in the dissociation process.
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  • 6
    ISSN: 1432-0630
    Keywords: 07.65 ; 42.55 ; 42.80
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract The application of the high-pressure chamber with a pressure transmitting medium (liquid at room temperature) to diode-laser tuning was found to be a useful method for high-resolution spectroscopy. Ammonia absorbtion spectra in the 10 μm region were recorded with a resolution approaching the Doppler limit.
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  • 7
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    Applied physics 21 (1980), S. 237-240 
    ISSN: 1432-0630
    Keywords: 42.55 ; 42.60 ; 34.50
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Selective single-line oscillation has been obtained from an NH3 laser in the range from 11 to 13 μm. Pumping of high pressure NH3−He mixture with theR(30) line of a TEA-CO2 laser made it possible to tune on more than 30 lines with the aid of a grating. However, such line tunable oscillation was not observed when theR(16) line was used for pumping. Reasons for this difference are discussed.
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  • 8
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    Applied physics 21 (1980), S. 319-321 
    ISSN: 1432-0630
    Keywords: 42.55 ; 42.60
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract We report the observation that the helical TE N2 laser can effectively be simplified by giving up the use of decoupling elements as well as by abolishing the segmentation of the electrode structure. Although, as a consequence of this simplification, the operating pressure range was slightly decreased, the output power could be improved by roughly 30%, a result which is attributed to the new electrode geometry exhibiting lower inductance and lower damping losses.
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  • 9
    ISSN: 1432-0630
    Keywords: 87 ; 42.55 ; 82.50
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract We report on first attempts for selective action on nucleic acid components, namely uracil and adenine, using picosecond light pulses. Selective action was achieved both in the case of irradiation of mixtures of bases and in the case of irradiation of mixtures of different nucleic acids components, which contain uracil and adenine.
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  • 10
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    Applied physics 22 (1980), S. 213-218 
    ISSN: 1432-0630
    Keywords: 42.55 ; 42.60 ; 42.65
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract We present periodic solutions, which are described in terms of Jacobian elliptic functions, for the steady state pulses from a laser system consisting of a pair of amplifiers of unequal relaxation time mode locked by a “fast” saturable absorber. The pulsewidth and the average power in the pulse are expressed interms of the system parameters through two different approaches, where detailed plots are given for one of the approaches. Summary of the characters to be possessed by the amplifier pair to ensure the reliable production of shortest possible pulses is given.
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  • 11
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    Applied physics 22 (1980), S. 277-281 
    ISSN: 1432-0630
    Keywords: 42.55 ; 52
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract An analytical model is applied to the concept of a solar-pumped MHD laser utilizing the CsXe excimer and Cs2 dimerA-X laser transitions. The model predicts practical gain coefficients on the excimer band for supersonic flow of a 2000 K, 20 atmosphere cesium-xenon plasma across a ∼10 kG magnetic field.
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  • 12
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    Applied physics 22 (1980), S. 421-427 
    ISSN: 1432-0630
    Keywords: 42.55 ; 47 ; 52
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract The operation of an electrically excited gasdynamic CO laser with closed-cycle gas flow is described. Details of the gasdynamics, the recompression, and the cooling of the flowing gas are given. The electrical discharge produces contaminating gas compounds—in particular CO2—which accumulate in the recirculating gas. The resulting transient behavior of the laser gas composition, the discharge characteristics, and the laser performance are studied and compared with the results obtained with the same CO laser in an open-flow system. It is found that the closed-cycle system may be operated for considerable time if the CO2 contamination is removed from the laser gas.
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  • 13
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    Applied physics 23 (1980), S. 15-19 
    ISSN: 1432-0630
    Keywords: 64.75+g ; 61.70T ; 42.55
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract The solubility of several dopants (Sb, Ga, Bi, In) in laser treated silicon has been investigated. The dopants were introduced by vacuum deposition followed by ruby laser irradiation. Their solubility was determined by Rutherford backscattering spectroscopy measurements in channelling and random conditions. In all cases, a maximum solubilityC S * , much higher than the equilibrium solubility limitC S 0 and independent of the pulsed laser energy density, was found. The values obtained are in good agreement with those calculated from a simple model based on phase diagram considerations, using the relationship: $$C_S^* = \frac{{C_S^0 }}{{k_0 }}k^* ,$$ wherek 0 andk * are the equilibrium and effective distribution coefficients. Finally, the existence of a new solubility limit for a laser treatment is discussed.
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  • 14
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    Applied physics 23 (1980), S. 127-130 
    ISSN: 1432-0630
    Keywords: 42.55
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Two new cw submillimetre lines optically pumped by the 9 μR(30) CO2 laser have been observed for14NH3 and assigned to thea(6,0)→s(5,0) transition and to its cascade transitions(5,0)→a(4,0) in thev 2=1 state. In addition, six new emission lines have been observed for NH2D, and one tentatively assigned to the (11,1)→(10,1) transition of ND3. Methylamine has also been investigated and twenty-eight new emission lines have been discovered.
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  • 15
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    Applied physics 23 (1980), S. 341-344 
    ISSN: 1432-0630
    Keywords: 42.55
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract An N2-laser of 19 ns pulse-duration and an energy of 30 mJ has been developed and examined. A dc preionization, a grooved electrode and a partial electrical screening of the discharge tube permit reproducible single-shot operation and yield a homogeneous beam.
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  • 16
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    Applied physics 24 (1981), S. 33-38 
    ISSN: 1432-0630
    Keywords: 42.55 ; 33.80
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract We report infrared laser emission in the region of 3 to 5 μm from sodium vapour optically pumped by a pulsed dye laser with wavelengths ranging from 585 to 610nm. Twophoton excitation processes are believed to be responsible for the primary excitation. Both molecular transitions (4 to 5 μm) between high lying states, and atomic transitions (52 S 1/2−42 P 3/2,1/2 at 3.41 μm) have been identified.
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  • 17
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    Applied physics 24 (1981), S. 267-272 
    ISSN: 1432-0630
    Keywords: 52 ; 42.55
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Detailed data of the minimum preionization electron density (MPED)n 0 necessary to initiate a homogeneous discharge mode in transverse gas discharges are computed. An upper limit for the inductance of the discharge circuit is set by the power balance during breakdown. The results are presented as functions of generalized parameters. Applicability of the computations is proved by experimental observations.
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  • 18
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    Applied physics 24 (1981), S. 341-348 
    ISSN: 1432-0630
    Keywords: 42.55
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract The presented theoretical model for a mode-locked Nd-glass laser simultaneously takes into account dynamics of the mode-locking dye, amplification saturation and radiation background. A systematic variation of laser parameters gives insight into the pulse formation process and allows to improve the laser design. The calculations show that it should be possible to decrease considerably the duration of light pulses of a mode-locked Nd-glass laser. Using a new mode-locking dye with a switching time of τ=2.7×10−12 s we obtained stable laser operation and a pulse duration of 1.7×10−12s.
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  • 19
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    Applied physics 25 (1981), S. 31-34 
    ISSN: 1432-0630
    Keywords: 35 ; 42.55 ; 42.65
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract The decay rates of the3 D 1 level of I–II and the 3s 2 level of neon have been measured by the magnetic-field power dip method. The decay rate at the zero-pressure limit is found to be 7.1 MHz/2π for the3 D 1 level. The collision cross-section for excited I ions with helium atoms equals 0.19×10−15 cm2.
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  • 20
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    Applied physics 25 (1981), S. 17-22 
    ISSN: 1432-0630
    Keywords: 42.55 ; 82.50
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract The characteristics of near uv dye lasers pumped with short duration, 308 nm pulses from a XeCl laser are described with particular emphasis on the parameters influencing high average power operation. The solvent is shown to effect the operation of all dye lasers studied, particularly the photochemical stability. Measurements of the efficiency, as a function of the integrated pump energy have been made for a series of dye-solvent combinations. With the best combinations, average output powers in excess of 1W and conversion efficiencies greater than 25% were obtained at a repetition rate of ∼100 Hz.
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  • 21
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    Applied physics 25 (1981), S. 273-274 
    ISSN: 1432-0630
    Keywords: 42.55
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Near-infrared laser action of atomic carbon was obtained using a hollow cathode discharge tube. Besides the known 1.4543 μm and 1.0691 μm laser lines, cw laser operation at 1.0683 μm, 0.9658 μm, and 0.9406 μm wavelength was observed for the first time. The source of carbon was due to dissociation of CO, CO2 or CH4 added to the He buffer gas.
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  • 22
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    Applied physics 25 (1981), S. 329-336 
    ISSN: 1432-0630
    Keywords: 42.55 ; 78.55
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract This work was an experimental investigation of a potential large-scale excimer laser system, in which a high-pressure KrF gas mix was pumped by the 4-MeV electron beam from an available linear accelerator. As a function of the mix and the pressure, fluorescence from KrF* and/or Kr2F* were produced with good efficiency. Comparing measured data with a kinetic model, it was found that the kinetics followed the “normal” patterns seen in low-energy electron pumping. The data fitting process also resulted in a new value for the three-body quenching rate constant for reactions involving Ar. A critical factor in the development of this laser will be an improvement in beam control over that afforded by a simple solenoidal magnet. The conditions necessary for lasing are predicted; no inherent limitations on scaling of the device were found.
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  • 23
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    Applied physics 21 (1980), S. 407-409 
    ISSN: 1432-0630
    Keywords: 42.55 ; 52 ; 85.60
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract A method is described for detection of CO2-laser power variations which requires no optical detector. It is based on plasma-tube impedance changes induced by the laser power flow within the cavity. A constant-current high-voltage power supply and a special equalizer are necessary to obtain a voltage proportional to the laser power. Details for the design of the equalizer are given. The detection scheme works for frequencies up to about 5 kHz and can be used for laser frequency stabilization or signature analysis.
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  • 24
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    Applied physics 22 (1980), S. 149-154 
    ISSN: 1432-0630
    Keywords: 42.55 ; 52
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract The stability of parallel pin electrode CO2-laser discharges, coupled by carrier diffusion only, against concentration of current in one column and subsequent transition into an arc, is investigated theoretically. A small signal description of the time dependent behaviour of a column with falling characteristic caused by a wall sheath of considerable width is used. It is shown that an inductance in series to each discharge is not able to avoid glow to arc transition, though enlarges the duration of the glow.
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  • 25
    ISSN: 1432-0630
    Keywords: 33 ; 82.50 ; 42.55
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Absorption and fluorescence spectra of rarefied vapors ofp-terphenyl, 1,4-bis-[2(5-phenyloxazolyl)]-benzene, 2,5-diphenyl-1,3,4-oxadiazole, 2,5-diphenyl-1,3-oxazole, 2,5-diphenylfuran are measured. Extinction coefficients, quantum yields of fluorescence and one-photon decomposition of molecules are determined for vapors excited by pulsed laser radiation at 266 and 355 nm in the temperature range from 200 to 400°C. It is shown that for all cases studied the one-photon decomposition is only a small part of the total quantum yield of the radiationless deactivation of the fluorescent state. Laser action has, for the first time, been obtained in 2,5-diphenylfuran vapor at 356 nm.
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  • 26
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    Applied physics 22 (1980), S. 171-174 
    ISSN: 1432-0630
    Keywords: 42.55 ; 82.50
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract A previous analysis that described loss of gain in a dye solution as a result of photochemical decomposition by pump photons is refined and is extended to the situation where impurities absorb at the pump wavelength. A limitation in the first paper is that it described only a single absorption depth in the medium at a constant pump fluxI p. The present examination includes the fall-off ofI p and integrates the total signal output with depth for a single-pass amplifier operated in the fully saturated gain condition. The equations are simpler, but as before loss of output, expressed in terms of a quantum yield of laser decayQ L, is minimized for a photochemically bleachable dye, and for one with high gain. Pumping in the vicinity of the absorption maximum is also advantageous.
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  • 27
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    Applied physics 22 (1980), S. 355-359 
    ISSN: 1432-0630
    Keywords: 32 ; 42.55
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    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Fluorescence spectra in the near infrared are observed of the dye Eastman 9860 and of new, faster mode-locking dyes. The quantum efficiencies are determined to be small with η≃10−3. The short fluorescence lifetimes are deduced from optical gain measurements. The fluorescence time-constants are found to have the same value as the corresponding absorption recovery times. Even laser action is observed in these fast saturable absorbers previously belieyed to be non-fluorescent.
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  • 28
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    Applied physics 23 (1980), S. 135-140 
    ISSN: 1432-0630
    Keywords: 42.55
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract A laser system capable of generating picosecond pulses of 2 ps duration and peak powers of up to 50 MW, tunable throughout the emission spectrum of the lasing medium is described. The system consists of a cw dye laser which is tuned and is actively mode-locked by means of a novel interferometer. Single-pulse amplification is achieved via a two-stage N2-laser-pumped amplifier arrangement. One of the most attractive features of the system here described is its inherent versatile broad tunability, which should allow, with different lasing media and pump sources, ps pulse generation from 400 to 700 nm using the same interferometer device.
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  • 29
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    Applied physics 23 (1980), S. 295-298 
    ISSN: 1432-0630
    Keywords: 41 ; 42.55
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    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract An analysis of stimulated emission of radiation by an electron beam passing through a periodic longitudinal electrostatic field is presented, and its use in a free-electron laser structure is discussed. The analysis is based on a coupled-mode calculation of the interaction between a waveguided electromagnetic mode and an electron-beam plasma with finite cross section. The dispersion equation derived applies to the collective as well as the single electron regime.
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  • 30
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    Applied physics 24 (1981), S. 45-48 
    ISSN: 1432-0630
    Keywords: 42.55 ; 42.65 ; 64
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract We investigated time-dependent effects related to the bistable operation of a CO2 laser with an intracavity nonlinear absorber (SF6). The response of the system to small perturbations was sensitively dependent on the operating laser line [P(12)→P(30)] of the 10.6 μm band. The narrow bistable region forP(12), due to a very narrow hysteresis loop, can be effectively utilized for optical switching, because of its pronounced sensitivity to variations in operational parameters. The maximum admissable beam blocking time (intracavity) for spontaneous return to lasing was measured forP(16), for a range of absorber pressures. This τm is related to the relaxation time of the upper level in the absorber.
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  • 31
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    Applied physics 24 (1981), S. 381-386 
    ISSN: 1432-0630
    Keywords: 33 ; 42.55
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    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract A tunable diode laser and a multipass optical cell are used to investigate the feasibility of performing radiocarbon dating by means of infrared spectroscopy. We show that the detection of14CO2 at concentrations of14C/12C≲10−12 is not limited by interferences from the background of normal CO2 molecules, provided the gas sample is cooled. Using short-time constants, the present sensitivity of the infrared technique is comparable to that of an ideal disintegration counter. The experimental results are extrapolated to long time constants to demonstrate that radiocarbon dating by infrared spectroscopy is feasible, and that carbon samples with a mass of less than 1 gm can be dated by this technique.
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  • 32
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    Applied physics 21 (1980), S. 95-114 
    ISSN: 1432-0630
    Keywords: 42.55 ; 42.60
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract The development of excimers and excimer lasers are reviewed. The excimers of the noble gases (Xe 2 * , Kr 2 * , Ar 2 * ) and of the noble gas halides (e.g. KrF, XeCl) which, respectively, radiate in the vacuum ultra-violet and ultra-violet regions of the spectrum are described in terms of their structure, spectroscopy and formation kinetics and the methods of pumping, operational characteristics and applications of the lasers are discussed.
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  • 33
    ISSN: 1432-0630
    Keywords: 35 ; 42.55 ; 42.80
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract A saturated absorption technique, using an actively stabilized cw dye laser has been developed to measure the saturation intensities of hyperfine transitions in a gaseous medium. Hyperfine lines belonging to theB-X system of molecular iodine have been investigated. The experimental method proposed, provides a means for measurement of the absolute value of the saturation parameter of the transition with an accuracy better than 10%. The behavior of the saturation intensity of some transitions with iodine pressure has been investigated in the range 30 m Torr→90mTorr.
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  • 34
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    Applied physics 22 (1980), S. 219-225 
    ISSN: 1432-0630
    Keywords: 42.55
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract A simple single particle model of a free-electron laser (FEL) amplifier has been used in a computer simulation to determine the maximum fractional conversion of electron kinetic energy to laser energy. The simulation results can be represented by a single universal curve. A simple scaling relationship for the length of the optimized constant period helix together with the universal curve permit one to predict maximum fractional energy conversion for any set of values of initial electron energy, initial laser intensity, magnetic field amplitude, and magnet period.
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  • 35
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    Applied physics 23 (1980), S. 299-302 
    ISSN: 1432-0630
    Keywords: 42.30 ; 42.55 ; 42.65
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract The spatial coherence function |Γ(s)| of ruby laser pulses has been measured by self-diffraction at a laser-induced grating depending on the distances between two points in the beam profile. The spatial coherence of the laser beam was changed by operating the laser in the fundamental transverse mode, in a transverse multimode and by applying different pump powers. The degree of spatial coherence was experimentally found to be a Gaussian, as described by the Collett-Wolf model. The new method for measuring the spatial coherence function |Γ(s)| is described and possible improvements are discussed.
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  • 36
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    Applied physics 23 (1980), S. 345-348 
    ISSN: 1432-0630
    Keywords: 42.55
    Source: Springer Online Journal Archives 1860-2000
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    Notes: Abstract New FIR emissions lines have been observed for HCOOH, D2CO and CD3Br. Assignments have been made of the HCOOH lines and for most of those of CD3Br. For D2CO, most of the new emissions showed a corresponding cascade transition.
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  • 37
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    Applied physics 24 (1981), S. 7-9 
    ISSN: 1432-0630
    Keywords: 42.55
    Source: Springer Online Journal Archives 1860-2000
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    Notes: Abstract Newly found reflection properties of the Fizeau wedge interferometer are shown to be of particular advantage in obtaining efficient multi-wavelength operation of dye lasers. Use is made of the fact that the reflecting Fizeau wedge can ensure at once a selective feedback for a given wavelength and quasi-total reflection in an other direction for all other wavelengths. Fully independent tuning of two 0.02 nm lines is obtained with short pulse (2 ns) N2-laser pumping using a single Fizeau wedge.
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  • 38
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    Applied physics 24 (1981), S. 233-238 
    ISSN: 1432-0630
    Keywords: 42.55
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract A synchronously mode-locked, cavity-dumped picosecond dye laser is described. The structure and intensity of the picosecond pulses measured under different conditions are reported. It was found that the structure of the pulses from the synchronously pumped dye laser depends critically on the length of the Ar+ laser pulses. At the shortest Ar+ laser pulses of about 70 ps the dye pulses are as short as 1.1 ps. With Ar+ laser pulses of 200 ps the dye laser pulses contains a broad satellite pulse which contains a large fraction of the total intensity. When a cavity dumper is added to the system one gets dye laser pulses 15–20 ps long with a substructure, which indicates incomplete mode-locking. Well mode-locked 1.5–2.0 ps pulses were obtained in the red part of the dye laser action spectrum, i.e. 620–650 nm for R6G, 595–608 nm for R 110 and 657–662 nm for RB, respectively. Addition of mode-locking dyes also improved the pulse quality at some wavelengths.
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  • 39
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    Journal of Applied Polymer Science 25 (1980), S. 1-13 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The influence of hydroxyl modifiers on the properties of Diels-Alder adducts-terpene hydrocarbons with maleic anhydride - was studied. The mechanical, thermal, and dielectric properties of the composition of Epidian 5 epoxy resin hardened with an adduct modified by ethylene glycol, propylene glycol, dipropylene glycol, glycerin, or hexanetriol are described.
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  • 40
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    Journal of Applied Polymer Science 25 (1980), S. 41-49 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Helium gas plasma treatment of low-density polyethylene (LDPE) yields much lower peel strength than oxidative treatment using chromic acid and oxygen gas plasma. The practical adhesion, the bondability retention, and the bond durability of oxidatively treated LDPE sheets, bonded with epoxy adhesives, have been compared with those of partially hydrolyzed LDPE-methyl acrylate surface grafts. The oxidized surfaces easily lose the bondability by light rubbing with tissue paper, solvent extraction, heat aging, and artifical weathering, whereas the grafted surfaces retain the bondability. The bondability loss is due to removal of the oxidized layer, and the bondability retention is due to retention of the surface homopolymer layer. Conventional antioxidants stabilize the grafted but not the oxidized surfaces against thermal oxidative degradation. The grafted LDPE joints have much higher bond durability in humid environments than those of the oxidized LDPE joints. The dry and wet peel strengths of oxidized LDPE joints are greatly improved by application of primers consisting of a base epoxy resin and organic solvents. An adhesion mechanism involving penetration of epoxy adhesives into the oxidized layers and subsequent reinforcement of the layers by curing of the penetrated epoxy is proposed.
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  • 41
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    Keywords: Chemistry ; Polymer and Materials Science
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    Notes: Glow discharge initiation of in situ polymerization of acrylic acid and other vinyl monomers incorporated in PET films was investigatigated. The influence of glow discharge conditions such as the gas used, plasma power, discharge current, and plasma treatment time on polymerization yield was determined. Though glow discharge effects are limited to the film surface, in situ polymerization of the vinyl monomers took place and the vinyl polymer could be found all through the film cross section. At short plasma treatment time only surface modification took place, while at longer treatment time bulk modification occurred, too. Good polymerization yields were obtained. Gel effect behavior was observed. Mechanical properties of the modified PET film were not changed, while the contact angle with water improved when polar vinyl monomers were used.
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  • 42
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    Journal of Applied Polymer Science 25 (1980), S. 127-137 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A study of postextrusion relaxation (shrinkage) rates identified two separate processes, only one of which is influenced by carbon black structure and surface area. One of these processes is thought to be a solidlike fast elastic recovery and was found to be influenced by carbon black and polymer characteristics. The other process reflected slow randomization of oriented molecular chains: it was mainly influenced by polymer nature and carbon black had almost no effect. In the previous paper of this series, work with various carbon blacks in SBR-1500 indicated that both types of polymer deformation originate within the converging flow region at the die entrance, where extensional flow takes place. In the present work the extensional flow behavior of five polymers (filled with various carbon blacks) was examined at elevated temperatures. The magnitude of shrinkage caused by molecular alignment was related to extensional viscosity of the rubbers. This confirms the hypothesis stated above. Extensional viscosity was measured using the previously described instrument, which is inexpensive to construct, easy to operate, and can be attached to any standard stress-strain tester. The characteristics of extensional flow are defined and it is shown that for polymeric materials it differs substantially from shear flow, since a rapid orientation of the molecular chains takes place during the extensional flow. The effect of carbon black on the extensional viscosity at elevated temperatures is illustrated.
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    Journal of Applied Polymer Science 25 (1980), S. 111-118 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Effect of temperature on the electrical conductivity of PVC-copper composites has been studied. The temperature coefficient of dc resistivity of composites with fillers containing negligible oxide content in the range of 77-303 K is positive, indicating metallic-type conduction. The temperature coefficient of dc resistivity of composites with fillers containing intermediate level of oxide at higher temperatures is negative, indicating a semiconducting behavior. Plots of log conductivity versus log frequency for composites in the insulating region show the hopping-type conduction.
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    Journal of Applied Polymer Science 25 (1980), S. 25-39 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Adhesive joints of hydrolyzed methyl acrylate grafts, bonded with epoxy adhesives, yield extremely high peel strength (adherend failure) in dry conditions. However, when the joints are exposed to humid environments, the peel strenght rapidly decreases with exposure time and then reaches a constant value (wet peel strength). Since the locus of failure changes from the adherend to the homopolymer layer with decreasing peel strength, the decrease is due to a decrease in mechanical strength of the homopolymer layer itself, which results from its swelling by water absorption. Many attempts to reduce the swelling of the homopolymer layer or to strengthen the swollen homopolymer layer were unsuccessful except (1) priming with epoxy solutions consisting of a base epoxy resin and organic solvents which can dissolve not only epoxy resins but also hydrolyzed poly(methyl acrylate) and (2) partial etching of the homopolymer layer by photo-oxidative degradation. All the results on the improvement in wet peel strength can be explained in terms of the penetration of epoxy resins into the homopolymer layer and subsequent curing of the penetrated epoxy resin.
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    Journal of Applied Polymer Science 25 (1980), S. 15-23 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The effect of orientation on the structure and transport properties of high-density polyethylene film has been studied. Microstructure was characterized using small-angle light scattering, birefringence, and wide-angle x-ray scattering. Water vapor and oxygen transmission rates were determined as a function of film draw ratio. The object of the present work is to correlate the effects of postprocessing conditions on the transport properties and morphology of linear polyethylene. High-density spherulitic polyethylene films were produced by blown film extrusion and subsequently oriented by longitudinal stretching in a postoperation. Various degrees of orientation were imparted to the films, with percent crystallinity, sample orientation and transport properties measured as a function of draw ratio. For the postoriented films, results indicate there was no significant change in percent crystallinity with increasing draw ratio although water vapor and oxygen permeability decreased substantially. This is attributed to the increased orientation of the crystalline and amorphous regions and rod-like and microfibril structure formation brought about by the drawing process. Lower processing temperatures result in increased orientation which improves the vapor barrier properties.
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  • 46
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: Graft copolymerization of methyl methacrylate onto wool was investigated in aqueous solution using potassium peroxydiphosphate as initiator. The rate of grafting was determined by varying monomer, peroxydiphosphate ion, temperature, solvent, and nature of wool. The graft yield increases with increase in monomer concentration. The graft yield increases significantly by increasing peroxydiphosphate ion up to 80 × 10-4mole/l.; with further increase of peroxydiphosphate ion the graft yield decreases. The rate of grafting increases with increase in temperature. The effect of acid-and water-soluble solvents on the rate of grafting was investigated and a suitable rate expression has been derived.
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  • 47
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    Journal of Applied Polymer Science 25 (1980), S. 433-447 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Changes in the dynamic mechanical properties of nylon 6 (α-form) under ultraviolet light irradiation were investigated. On irradiation with spectrally dispersed ultraviolet light in the wavelength range of 219-415nm, the dynamic modulus E′ and the density of nylon 6 were increased below about 300nm. It was found that the increment in E′ and the density were the result of crosslinking. When E′ was measured with time elapsed during irradiation by light of 253.7 nm, E′ initially decreased with time, increased at a longer time, and then reached a limiting value asymptotically. From the result of the change in E′ with time, it was assumed that the scission and crosslinking reactions occur simultaneously during ultraviolet light irradiation. Thus, the change in E′ with elapsed time was exppressed by the equation E′t = E′0 exp (-k1t) + E′∞[1 - exp (-k2t)], where E′t is the dynamic modulus at time t, E′0 is the E′ at t = 0, E′∞ is the limiting value of E′, and k1 and k2 are the rate constants. The apparent activation energies for k1 and k2 were 3.23 and 2.50 kcal/mole, respectively, and the former value agreed with the activation energy for the scission of the amide groups. The effects of the photodegradation on the temperature dispersion of nylon 6 were also investigated. On irradiation with light at 253.7 nm, the α-relaxation which appeared at about 90°C was broadened and the intensity of the γ-relaxation at -95°C in the tan δ-versus-temperature curve was lowered. The β-relaxation which appeared at -45°C for the wet nylon 6 decreased its intensity.
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    Journal of Applied Polymer Science 25 (1980), S. 499-510 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Several physical methods were used for the determination of the mean molecular weight of polyethylene glycols (PEG). Gas chromatography proved to be the best method to obtain a molecular weight of PEG lower than 600 by using Tenax as a stationary phase. Reverse gas chromatography was long but valid for PEG between 400 and 3000. Viscosity measurements gave more suitable values by taking different Mark-Houwink constants according to the molecular weight of PEG. Gel permeation chromatography using the universal calibration method was shown reliable, and by means of three μ-Styragel phases (100, 500, and 104 Å) the molecular weight range between 200 and 20,000 was covered. Infrared measurements were related to the molecular weight by taking the OH absorbing band, and a result for PEG of 5000 or less was obtained. Vapor pressure measurements as made in tonometry were an accurate and sensitive method.
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    Journal of Applied Polymer Science 25 (1980), S. 529-534 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The Rheovibron viscoelastometer is useful for obtaining dynamic tensile, shear, and bending mechanical properties of films and fibers over a wide teḿperature range. In recent years a modification that makes measurement on materials in a liquid or gas medium possible has been reported. A new compression grip and procedure were used for measuring dynamic mechanical properties of a fiber mass in the compression mode using the Rheovibron instrument. The dynamic compression properties on nylon, polyester, and acrylic fibers are presented.
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    Keywords: Chemistry ; Polymer and Materials Science
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    Notes: Many UV-cured acrylates, epoxides, and thiol-enes suffer a dramatic, reversible loss of tensile strength during exposure to moisture and/or elevated temperatures. Certain formulations are especially sensitive and lose up to 95% of their dry tensile strength in a humid environment. Glass transition temperatures of these materials are also much lower in high humidity than they are in low humidity. It is proposed that these losses of physical properties in high humidity are due to reduced intersegmental attractions of polymer chains caused by preferential hydrogen bonding to water.
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    Journal of Applied Polymer Science 25 (1980), S. 575-588 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: As part of a continuing study of nonisothermal rheology (meaning the simultaneous application of strain and temperature changes), we here consider the behavior of polystyrene near the glass transition temperature Tg. In particular, we measured the increase of the apparent Tg as the cooling rate is increased from 0.003 to 4.5°C/sec. This change (up to 16°C increase) has both practical and theoretical implications. For enhancing the mechanical properties of a glassy product, one desires maximum orientation (stress) just prior to quenching; the optimum deformation/temperature strategy for maximizing stress is affected by the level of Tg. By using a nonisothermal strategy we were able to produce higher frozen-in orientations, and thus higher mechanical properties, than have been previously reported. For a theoretical understanding of the rubbery state just prior to quenching, we used the generalized time-temperature superposition of our prior work; we found that a modified shift factor of the form aT(T,TRg), where TRg refers to a rate-dependent Tg, gives an improved fit to data but is not by itself adequate.
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    Journal of Applied Polymer Science 25 (1980), S. 615-625 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Certain aspects of moisture sensitivity for selected polyurethane-polyether block copolymers were investigated. Exposure to ambient conditions tended to raise the impact velocity for projectile penetration and to decrease the brittleness of these materials. High values of relative humidity, whether applied immediately or after a time delay, led to softening and ductile response of an initially brittle formulation. Immediate desiccation of the brittle formulation caused retention of hardness and brittleness, whereas after prior humidification, desiccation removed much water but did not reverse the prior transition to ductile response to impact. Measurements were made of water sorption and desorption exhibited by this brittle formulation.
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    Journal of Applied Polymer Science 25 (1980), S. 683-689 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Cellulose peroxides derived from hydrogen peroxide and cellulose derivative into which a ketone group is introduced by reaction with methyl vinyl ketone were investigated. The amount of peroxide formed on the cellulose substrate increased linearly with increasing carbonyl content of the sample, and sulfuric acid activated the formation of peroxide. The cellulose peroxide was gradually decomposed at 60°C in aqueous medium, and the decomposition was accelerated by addition of ferrous salt or irradiation with light of λ 〉 300nm. Grafting was initiated by adding methyl methacrylate to the thermal decomposition system under nitrogen. The formation, stability, thermal decomposition, and structure of the cellulose peroxide were discussed in comparison with one derived from aldehyde cellulose and hydrogen peroxide.
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    Journal of Applied Polymer Science 25 (1980), S. 711-716 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
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    Journal of Applied Polymer Science 25 (1980), S. 739-746 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Several polyurethanes were prepared from poly(ethylene adipate)glycol, 4,4′-diphenylmethane diisocyanate, 1,4-butanediol, or 3,3′-dichloro-4,4′-diaminodiphenylmethane. Thermomechanical curves were determined for all investigated systems, and the glass transitions found thereof formed the basis of subsequent analysis. The analysis showed that the investigated systems belonged to those polyurethanes that can undergo microphase separation. It was also shown that the separation in the diamine-extended elastomers was less sensitive to changes in chemical composition than in the diol-extended systems. The diamine-based polyurethanes were also closer to the ideal separation than the diol-extended elastomers. Examinations of elastomers of varying amount of chemical crosslinking revealed a joint action of the crosslinking and microphase separation in determining mechanical properties of the systems. Together with swelling measurements, the examinations showed that optimum mechanical properties were obtained while keeping a very careful balance between these two factors.
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    Journal of Applied Polymer Science 25 (1980), S. 761-769 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The influence of relative molecular weight on rubber thermo-oxidation in air at 130 ± 1°C has been studied by means of infrared spectroscopy. The carbonyl group formation in single fractions of natural rubber has been measured. It was found that the development of kinetic curves ΔAC=O = f(t) corresponds for both fractionated and unfractionated extracted samples. Kinetic curves of natural rubber formation are characterized by an induction period τ. Its magnitude is a function of molecular weight up to the value [η] = 0.2 m3/kg, and then stays invariant to changes in [η]. In the range of low values of the internal viscosity up to 0.2 m3/kg, the dependence τC=O = f[η] has an exponential character as a consequence of the statistical character of chains breaking down during the degradation. It has been proved that the reciprocal value dependence of the mean viscosity molecular weight of unfractionated acetone-extracted natural rubber on the length of induction period is linear. The change in double-bond amount during the oxidation is not reflected in the induction period determined by infrared spectroscopy.
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    Journal of Applied Polymer Science 25 (1980), S. 795-807 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: In discontinuous fiber-reinforced composites, the shear strength at the fiber-matrix interface plays an important role in determining the reinforcing effect. In this paper, a method was devised to accurately determine this shear strength, taking the strength distribution of glass fiber into consideration. Calculated strength values based on the shear strenght obtained by the method were in better agreement with the experimental observations than those calculated by employing the shear strength obtained on the assumption that the fiber strength was uniform. The tensile strength of composites increases with increasing aspect ratio of the reinforcing fibers. This trend is almost the same regardless of the kind of matrix, the nature of interfacial treatment, and the environmental temperature. When composites are reinforced with random-planar orientation of short glass fibers of 1.5 times the mean critical fiber length, the tensile strength of composite reaches about 90% of the theoretical strength of composites reinforced with continuous glass fiber. Reinforcing with glass fibers 5 times the critical length, the tensile strength reaches about 97% of theoretical. However, from a practical point of view, it is adequate to reinforce with short fibers of 1.5-2.0 times the mean critical fiber lenght.
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    Journal of Applied Polymer Science 25 (1980), S. 635-640 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The lateral order factor of four Indian varieties of silk, viz., Mulberry, Tasar, Eri, and Muga, were determined by electron diffraction technique and compared with that determined by x-ray diffraction. The profiles of the 002 and 201 reflections in Mulberry were better resolved by the electron diffraction technique.
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    Journal of Applied Polymer Science 25 (1980), S. 665-682 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The network segment density (γg) by solvent-swollen compression modulus of gum stocks and of stocks containing nonreinforcing fillers was calculated to be 6.6093 × 10-9h0Sf/φBd2 in mmole/m3 of gel at 25°C, where h0 is the height of the unswollen sample in cm, S is the slope of the height versus applied weight curve in g per mil (0.001 in.), φB is the volume fraction of binder, d is the diameter of the initial sample in cm, and f is a factor equal to (1- φs/φB)1/3/(1- φS)2/3, where φS is the volume fraction of extract. The volume fraction of crosslinked polymer containing nonreinforcing fillers at equilibrium in a solvent (V2) was determined for the cases where the filler is insoluble and partially adheres to the binder, where the filler is partially solube and there is no binder-filler adhesion, and where the filler is completely soluble in the swelling solvent. The relations were tested and found to hold for polyester-polyurethane stocks containing plasticizer and soluble and insoluble fillers. Log V2 fell on single straight-line curves with respect to log γg for gum stocks and filled stocks both when V2 was measured in solvents which dissolved none or dissolved part of the fillers.
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    Journal of Applied Polymer Science 25 (1980), S. 691-702 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Thermal analysis of cotton samples grafted with triallylphosphate (TAP) and 2,2,2-tribromoethyl acrylate (TBEA) was carried out. Grafting of poly-TAP causes a significant decrease in the decomposition temperature of cotton. The cotton decomposition is acid catalyzed by H3PO4 formed during the decomposition of the grafted poly-TAP. The HBr evolved during decomposition was monitored continuously during thermal analysis of cotton grafted with poly-TBEA. No significant flame-retarding effect by HBr was found. Since grafted poly-TBEA causes a decrease in the decomposition temperature of cotton, it is suggested that the flame retardant mechanism for poly-TBEA in cotton occurs mainly in the solid phase before most of the HBr is released.
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  • 61
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    Journal of Applied Polymer Science 25 (1980), S. 731-738 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The ability of adsorbing iodine in different organic solutions by chitosan was studied by sorption isotherm measurements. The ability was found to be larger in polar solvents than in nonpolar solvents. The form of the chitosan samples, such as film, powder, and flake, had no influence on the adsorption behavior. On the other hand, chitin had only small adsorbing ability of iodine. It is concluded that the adsorption of iodine is caused by charge - transfer complexes between aminogroups of chitosan and iodine molecules, but their structure differs from that of inclusion compounds as seen in amylose-iodine complexes. The adsorption was also studied on chitosan films with different degrees of acetylation.
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  • 62
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    Journal of Applied Polymer Science 25 (1980), S. 747-759 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Thermolysis and hydrogenolysis of polyethylene under steam pressure were carried out by batchwise autoclave in the recovery of liquid petrochemical resources from waste polymers. Thermolysis of polyethylene under steam pressure occurred in the temperature range 400-475°C and reaction pressures up to 213 bar. The presence of steam is advantageous for an increase in liquid products and 450°C is an appropriate temperature for the formation of low molecular aromatic compounds. Hydrogenolysis of polyethylene was studied at 450°C and initial hydrogen pressure range of 10-100 bar under steam pressure. Over 80 wt % of the low-boiling product was converted to saturated hydrocarbons at 40 bar hydrogen pressure, which corresponds to 1 mole hydrogen to 1 mole monomeric unit of polyethylene. The schemes for the thermolysis and the hydrogenolysis, especially the aromatization, are discussed.
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    Journal of Applied Polymer Science 25 (1980), S. 841-854 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The study of the effect of sodium poly(styrene sulfonate) addition to suspensions of fibers, in the presence of aluminum salts as adsorption aids, revealed the retention effect of fine solids during sheet formation. Polyelectrolyte adsorption also causes an increase of bounding energy in the web. It is shown that the improvement observed for the dry strength properties of paper is a consequence of these two effects. (In this paper the words “fine solids” or “fines” indicate the parts of the cellulosic material which filtrates through a 150-mesh screen, regardless of its nature.)
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    Journal of Applied Polymer Science 25 (1980), S. 1049-1058 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Molecular weight distributions, moments and the polydispersity indices were computed for AB-type condensation polymerization in an ideal continuous-flow-stirred tank reactor for monomers not following the equal reactivity hypothesis. The model considers the rate of reaction between monomer and monomer to be R times that characterizing the reaction between any other species in the reaction mass. It is found that the polydispersity indices in these reactors are substantially larger than values obtained in batch reactors. Also, the molecular weight distribution splits into two curves - one for odd-order homologs and the other for even-order ones for R 〉1. For R 〈 1, substantial amounts of unreacted monomer are present in the exit stream, and curve splitting does not occur.
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    Journal of Applied Polymer Science 25 (1980), S. 1087-1094 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Thermal behavior of graft copolymers of polyvinyl chloride with polystyrene prepared by using a cationic initiator (AlCl3) was evaluated by measurement of rates of dehydrochlorination in nitrogen atmosphere. With increase in the extent of grafting the rates were found to decrease. Dynamic thermogravimetric analysis revealed an overall improvement in thermal stability of copolymers. Development of polyene sequences in degraded polymer samples was evaluated by measurement of electronic absorption spectra. In comparison to PVC, graft copolymer samples had fewer conjugated double bonds.
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    Journal of Applied Polymer Science 25 (1980), S. 1095-1104 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: In our previous article on the photodegradation of polypropyle (PP), the effect of ferric chloride (FeCl3) accelerating the formation of peroxy radical and depressing the formation of alkyl radical were reported. In the present article, the influence of FeCl3 on model compounds of PP was examined using electron spin resonance (ESR) spectrometry. The following compounds were employed as models of PP, including its irregular structures: 2-methylpentane (2-MP), 2,4-dimethylpentane (2,4-DMP), 2-methyl-4-pentanone (2-M4P), 2,6-dimethyl-4-heptanone (2,6-DM4H), 2-methyl-1-pentene (2-M1P), and tert-butylhydroperoxide (t-BuO2H). FeCl3 accelerated the formation of alkyl radicals for 2-MP and 2,4-DMP, alkyl and acyl radicals for 2-M4P and 2,6-DM4H, and alkyl radicals for 2-M1P. As no definite effect of FeCl3 was observed for n-pentane and 2-octanone, FeCl3 was assumed to attack saturated hydrocarbons, ketones at a tertiary carbon-hydrogen bond, and hydrocabons at an allylic hydroge, leading to easier photodegradations. FeCl3 was also effective for the photodegradation of t-BuO2H using λ 〉300 nm, so that FeCl3 is believed to contribute also to the photodegradation of PP under the same irradation conditions. The catalytic effect of FeCl3 in photodegradation seems to origirate in a redox reaction.
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    Journal of Applied Polymer Science 25 (1980), S. 1145-1155 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Compositional analysis of 2,6-dimethyl-1,4-phenylene oxide (PPO) and styrene homopolymer blends was accomplished using infrared spectrometry and pyrolysis gas chromatography. In infrared measurements the 1030/700 cm-1 absorption ratio provides percent PPO in the blends within ±3% of the actual value but with a σ% of ±10. In pyrolysis GC measurements, four peaks resulting from the fragmentation of the PPO molecule have been investigated for quantitation. One of these peaks provides results with ±2% of the PPO present with a σ% of 7 when the percent PPO in the blend is above 20.
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    Journal of Applied Polymer Science 25 (1980), S. 1263-1271 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The influence of hydrofuramide (a reaction product of furfural and ammonia) on the network structure and overall kinetics of thiuram vulcanization of natural rubber is reported. The nature of the network structure of the thiuram vulcanizates in the presence and absence of hydrofuramide was determined using triphenyl phosphine (Ph3P) as a chemical probe. The presence of hydrofuramide produces structural complexity of the vulcanizate. The overall kinetics of thiuram vulcanization follows a first-order-rate law in the presence as well as in the absence of hydrofuramide. The rate constant increases while the energy of activation decreases in the presence of hydrofuramide.
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    Journal of Applied Polymer Science 25 (1980), S. 1217-1244 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: An experimental study of the viscosity and principal normal stress difference of a polystyrene melt filled with aramid (Kevlar), glass, and cellulose fibers is reported. The influence of loading level and mastication on the rheological properties is discussed. The effects of mixing and mastication on fiber damage are considered. Glass fibers break down rapidly to very small aspect ratios, while aramid shows a “kinked” structure, with kinks occurring every 100 μm. A mechanism is proposed for fiber breakage based on buckling during rotation in shear flow. It is found that addition of fibers increases the viscosity in the same manner as a reduction in temperature, and data may be superposed by reduced plotting. This indicates that the viscosity increase is due solely to enhanced viscous dissipation in the matrix and not to interparticle forces as is the case with smaller particles. The principal normal stress difference increases at fixed shear stress with fiber loading. The extent of increase depends upon fiber loading, aspect ratio, and modulus.
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    Journal of Applied Polymer Science 25 (1980), S. 1673-1684 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Dielectric, x-ray diffraction, density, thermomechanical, and thermogravimetric studies on polyacrylonitrile (PAN), poly[acrylonitrile-(2 methacryloyloxy)ethoxytrimethylsilane] [poly(AN-2MAETMS)], and poly[acrylonitrile-(2 methacryloyloxy)propoxytrimethylsilene] [poly(AN-2MAPTMS)] copolymers have been carried out for investigating their structure. The glass transition temperature as indicated from the dielectric and thermomechanical analysis data are lower for the copolymers as compared to PAN. Crystallinity is influenced by the introduction of the silylated acrylic comonomer units but the crystalline lattice remains similar to that of PAN. The changes obseved in the various properties of these coplymers clearly suggest a more closely packed structure of poly(AN-2MAETMS) than poly(AN-2MAPTMS), and the uninterrupted PAN sequences are longer in the former. Thermal stability of copolymers has also been investigated.
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    Journal of Applied Polymer Science 25 (1980), S. 1655-1671 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Biodegradative conversion of 14C present in high-density (linear) polyethene (HDPE) film to respiratory 14CO2 during a two-year aerated cultivation with soil or with Fusarium redolens dropped from 0.36% by weight to less than 0.16% by weight when the HDPE film was deprived from most of its low molecular components by extraction with cyclohexane. Decrease of 14CO2 production after extraction could be observed in different abiotic aging cultures. This is direct evidence for a primary utilization of the short-chain oligomeric fraction of the main crystalline materials. The extractable oligomeric fraction of HDPE was analyzed by gel permeation chromatography (GPC), and Mn 1049, 1088, and 1297 were found in untreated, aged, and biodegraded materials, respectively, indicating that microbes can oxidize somewhat longer polyolefin chains than aboitic forces do during aging. The limited degradation of HDPE confined to extractable material is comparable to the degradation of straight-chain n-alkanes and presumably proceeds according to similar mechanism. Such material (n-alkanes) can exit in the interstitial spaces between the crystalline lamellae as fringed micelles which infiltrate these cavities as amorphous clusters but are also produced to some extent during aging and weathering. Protection of HDPE by antioxidant (a sterically hindered phenol) resulted in an inhibition of microbiological catabolism of 14C to 14CO2. Aging was also suppressed in this way, indicating that although remnants of the supported CrCO3 polymerization catalyst are responsible for a slight but cumulative abiotic oxidation of the unprotected polymer, this effect will be counteracted too by the antioxidative additive. As biological degradation is superimposed on the chemistry of aging, a mutual synergism between the two effects is feasible.
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    Journal of Applied Polymer Science 25 (1980), S. 1703-1713 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The tensile behavior of blends of linear polyethylene (PE) and isotactic polypropylene (PP) was examined in relation to their morphology. Yield stress increases monotonically with increasing PP content, while true ultimate strength is much lower in all blends than in the pure polymers as a result of early fracture. The blends fail at low elongation because of their two-phase structure, consisting of interpenetrating networks or of islands of PE in a PP matrix, as shown by scanning electron microscopy of fracture surfaces and transmission electron microscopy of thin films. While spherulites in PP are very large (∼100 μm in diameter), addition of 10% or more of PE drastically reduces their average size. This, together with the profusion of intercrystalline links introduced by PE, may be associated with maximization of tensile modulus in blends containing ∼80% PP. Introduction of special nucleating agents to PP reduces average spherulite size and is accompanied by slight improvements in modulus. Thin films of blends strained in the electron microscope neck and fibrillate in their PE regions, but fracture cleanly with little fibrillation in areas of PP.
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    Journal of Applied Polymer Science 25 (1980), S. 1745-1753 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: Heat treatment of nylon 6,6 in the temperature range of 100-175°C in the presence and absence of a nonionic surfactant (Triton X-100) had little effect on the physical properties of the nylon, although the density of the nylon increased with increasing heat treatment temperature. The moisture regain value for the treated nylons did not change substantilly, whereas the overall wettability of the heat-treated nylon in the presence of nonionic surfactant showed a marked improvement. Both heat treatment of the nylon alone or in the presence of surfactant had a substantial effect on the uptake of three 1,4-substituted anthraquinone dyes on the nylon and on the resultant color of the dyed nylon.
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    Journal of Applied Polymer Science 25 (1980), S. 1755-1774 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The permeabilities and diffusivities of methane, ethane, propane, n-butane, and isobutane in commercially available poly(tetrafluoroethylene) (TFE) and poly(fluoroethylene-propylene) (FEP) Teflon have been measured in a Pasternak-type permeation cell. Experiments were carried out at upstream hydrocarbon partial pressures up to 50 torr (1000-60,000 ppm gas phase concentration) and temperatures from 40 to 195°C with films of 0.0508 and 0.127 mm thickness using nitrogen as carrier gas on the upstream and downstream sides of the membrane. The transient and steady-state permeation data are described well by a combination of Henry's law and Fick's law with a concentration-independent diffusion coefficient. Linear Arrhenius plots of both permeabilities and diffusivities were obtained. Linear correlations were found both between the activation energy for diffusion and the square of the gas molecule diameter, and between the logarithm of solubility at 90°C and the penetrant boiling point. Separation factors for binary mixtures of hydrocarbons were measured for TFE at 140°C and found to be similar to those predicted by individual permeabilities in most cases. Measurements with mixed gases were not made for FEP Teflon, but selectivities of FEP are expected to be similarly well described by the ratios of the pure gas permeabilities at the low partial pressures studied. The effect of annealing FEP Teflon for 24 hr at 200°C was found to produce an average of 20-30% reduction in solubility as well as a 9% increase in the activation energy for diffusion compared to as-received films. These effects are believed to be due to increased crystallinity in the sample upon annealing.
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    Journal of Applied Polymer Science 25 (1980), S. 1789-1792 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
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    Journal of Applied Polymer Science 25 (1980), S. 1799-1806 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
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    Journal of Applied Polymer Science 25 (1980), S. 1825-1831 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A method is developed to estimate the composition of a powder mixture using breadths of over-lapping x-ray diffraction (XRD) lines. The application of the method is illustrated for analyzing blends of cotton and jute.
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    Journal of Applied Polymer Science 25 (1980), S. 1839-1859 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The pyrolysis of organic waste polymers to produce fuels and chemicals is of interest to augment petroleum-based processes. The wide variety of pyrolysis products of low yield and the uncertain role that heat transfer rate plays in determining these have been deterrents to utilization in the past. A possible approach to increased selectivity for products is to heat them rapidly and homogeneously with the aim of narrowing the product distribution. A very rapid means of homogeneous heat transfer throughout the substrate is microwave heating. A laboratory study has been done to determine what effect high-intensity microwave energy has on the thermal degradative pathways of cellulose. The product distribution found when cellulose is pyrolyzed in the absence of a microwave discharge is similar to that found in conventional furnace pyrolysis. The major products are levoglucosan (27%), carbon dioxide (2-5%), water, and charred residue. However, the total heat-up and reaction times for even large pellets are reduced to less than 2-3 min when high-intensity microwave irradiation is employed. Effects of pressure and microwave power are reported. Low external gas temperature also prevents secondary reactions.
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    Journal of Applied Polymer Science 25 (1980), S. 1861-1866 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The tensile strength and ultimate strain of polypropylene fibers were measured by the creep fracture method at various temperatures. The tensile strength against time-to-break curves at various temperatures, which were plotted on log-log scales, were superposed by shifting the curves along the logarithmic time-to-break axis, and the composite curve of the tensile strength as a function of a reduced time to break was obtained. On the other hand, to construct the composite curve of ultimate strain from the ultimate strain against time-to-break curves at various temperatures, shifting the curves along the logarithmic ultimate strain axis was required in combination with shifting along the logarithmic time-to-break axis. The temperature dependence of the shift factor aT followed an equation of the Williams-Landel-Ferry (WLF) form. The volume fraction of free volume at the glass transition temperature and the coefficient of thermal volume expansion, which were calculated from the WLF coefficients determined for the polypropylene fibers, are almost the same as those known as “universal values” for amorphous polymers.
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    Journal of Applied Polymer Science 25 (1980), S. 1931-1942 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Processes aimed at forming high-performance fiber morphologies from rigid, semirigid, and flexible polymers have been analyzed. Routes that rely at least partially on the favorable thermodynamic consequences of conformational rigidity imparted by intramolecular and polymer-solvent interactions are shown to offer much greater promise than those that rely entirely on externally applied deformation.
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    Journal of Applied Polymer Science 25 (1980), S. 1943-1950 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: On the basis of standards of identification of substances in the additive system of polyethylene has been performed. Different methods for separation such as adsorption thin-layer chromatography, high-performance liquid chromatography with chemically bounded phases, and gas chromatography have been used. The fir al identification has been made with mass spectrometry. The substances have been extracted from polyethylene with hexane and chloroform.
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    Journal of Applied Polymer Science 25 (1980), S. 1969-1989 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The preparation of a novel asymmetric membrane cast from a homogeneous mixture of poly(4-vinyl pyridine) and cellulose acetate is described. The two polymers were found to be compatible in the presence of Lewis acids, yielding hydrophilic homogeneous alloys when properly prepared. Asymmetric membranes were cast from a six-component dope mixture containing chloroform, methanol, acetone, and formamide. The as-cast solution, when coagulated in water at ambient temperature, yields a highly plasticized anisotropic matrix which solidifies into a glassy state as the chloroform slowly diffuses into the water. The membranes, following this stage, exhibit a semipermeable dense skin that produces high fluxes and salt rejections when tested in a high-pressure reverse osmosis mode (no annealing is required). The anisotropic morphology was confirmed by scanning electron microscopy studies which revealed a dense skin resting on a highly porous, open-celled foamlike structure. This structure does not collapse upon drying and retains its original wet dimensions. Brief attempts to quaternize the matrix are also reported.
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    Journal of Applied Polymer Science 25 (1980), S. 1723-1735 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Effect of sorbed water on dielectric and mechanical properties is studied for three kinds of polyion complex (PIC) membranes formed from equal moles of polyanion [poly(sodium 4-vinylbenze-sulfonate)] and three polycations of different structural isomerisms [poly(4-vinylphenethyltriethylammonium bromide), poly(3-vinylphenethyltriethylammonium bromide), and random copolymer of these monomers]. Sorption isotherms and swelling characteristics indicate that PIC of parapolycation includes more water microphases than PIC of meta-polycatio. Complex dielectric constants of three PICs with varied water contents are measured at frequencies from 10 Hz to 100 kHz and the relaxation is analyzed in terms of the heterogeneous structure. Stress-elongation relationships of PICs equilibrated with water and aqueous NaBr indicate that yield and break stresses are higher for PIC of meta-polycation than that of para-polycation and decrease with increasing NaBr concentration above 0.1M.
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  • 84
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    Journal of Applied Polymer Science 25 (1980), S. 1775-1780 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Operation of an improved design of a vapor pressure osmometer for polyolefins at 140°C is described. Reproducibility of ±10% of the measured number-average molecular weight (Mn) was obtained with a maximum Mn of about 45,000-50,000. Results are reported for some standard and commercial, linear and branched polyethylenes and for commercial polypropylenes.
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  • 85
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    Journal of Applied Polymer Science 25 (1980), S. 1785-1788 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
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  • 86
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    Journal of Applied Polymer Science 25 (1980), S. 1813-1813 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
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  • 87
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    Journal of Applied Polymer Science 25 (1980), S. 1875-1882 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The chemical structure of polyurethane modified by BHET is correlated with its mechanical and dynamic mechanical properties. Evaluation of this amorphous elastomer by means of stress-strain tests and transition temperature measurements reveals that incorporation of the BHET structure into the soft polyester segment affects the domain structure and, in turn, the entire mechanical behavior of polyurethane. It is also shown that polyurethane has a wide range of Tg and secondary transition temperature by varying the ratio of BHET to EG as well as the ratio of TDI to polyester polyol.
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  • 88
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    Journal of Applied Polymer Science 25 (1980), S. 1961-1968 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Films of poly(methyl methacrylate) (PMMA), polystyrene, and a styrene/acrylic terpolymer have been cast from solutions of varying thermodynamic quality and the film properties studied by inverse gas chromatography and by critical surface tension measurements. Surface properties of the non-polar polystyrene were independent of solvent medium, but significant variations in these properties were observed in the case of PMMA and the terpolymer. Solvent balance also appeared to affect the bulk properties of the latter films, as judged by the penetration rates of interacting liquids. The observations indicate the feasibility of controlling film properties of the solid by the appropriate selection of solution media; a time-dependent variation in solid properties is to be expected, however, as the film structure attains an equilibrium state.
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  • 89
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    Journal of Applied Polymer Science 25 (1980), S. 2007-2017 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Europium(III) chelates of dibenzoylmethane (DBM) (1) and β-diketone-containing polymers, i.e., poly(p-benzoylacetylstyrene) (2) and poly(aryl β-diketone) (3), were prepared. In the polymer 2 the β-diketone moiety is attached to the phenyl ring, and for polymer 3 the β-diketone group is incorporated in the linear chain. The chelate structures were confirmed by measuring IR spectra, TGA, and DTA. The fluorescence emission intensity was measured on fine powder samples. For the composite samples of Eu(DBM)4 in polystyrene, the fluorescence intensity was found to increase linearly with increasing Eu content. However, for Eu coordination polymers, the intensity reached a maximum at Eu3+ content as small as 1 wt % and remained constant on further increasing the Eu3+ content. When the fluorescence intensities of Eu complexes were compared under the same conditions, namely, 1 wt % Eu, at which Eu-2 and Eu-3 show nearly maximum intensity, the order was found to be Eu-1 〉 Eu-2 〉 Eu-3. These phenomena were accounted for by the differences in the coordination number of the Eu complexes.
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  • 90
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    Journal of Applied Polymer Science 25 (1980), S. 2105-2107 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Fibrillar size of native cellulose was studied in detail by electron microscopic and x-ray techniques. Samples included natural fibers of cotton and ramie as well as algal and bacterial celluloses. Results indicated smaller sizes for cotton and ramie than was previously reported in the literature and a possible difference in fibrillar sizes among celluloses.
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  • 91
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Kinetic data are reported for the fast polymerization of a thermoplastic polyurethane under conditions similar to that of commercial reaction injection molding (RIM). The components were a 2000 molecular weight polyester polyol, butanediol and 4,4′-diphenylmethane diisocyanate. Three catalysts-dibutyltin dilaurate, phenyl mercuric propionate, and triethylenediamine-as well as uncatalyzed formulations were studied. Kinetic parameters were obtained by numerically fitting adiabatic temperature rise data with both second-order and hyperbolic models. The hyperbolic model gave consistently better fits and is supported by mechanistic studies in the literature. Activation energies compare well to literature values. The uncatalyzed rate was found to be significant. The kinetic parameters obtained by this method are useful measures of catalyst performance in the RIM systems. Moreover, the models provide a conveient way to predict the extent of reaction during the production of parts by the RIM process. The shape of the reaction pathway (extent of reaction time) may be important in the development of physical properties of polymers produced by the RIM process. Physical properties for these samples compare favorably to those for a conventionally produced (batch) polyurethane of the same formulation.
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  • 92
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    Journal of Applied Polymer Science 25 (1980), S. 2363-2372 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: In a study of polyacrylamide in solutions we have required the rapid characterization on chromatographies. The application to the aqueous solution of the GPC using controlled-porosity glass has been examined from both the viewpoint of the effect of salt addition and the GPC mechanism. An adequate addition to neutral salt, 0.005M KCI to the eluent, gave rise to the elution behaviors being in accord with the hydrodynamic volume concept of the GPC separation.
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  • 93
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    Journal of Applied Polymer Science 25 (1980), S. 2435-2438 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Additional Material: 3 Ill.
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  • 94
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    Journal of Applied Polymer Science 25 (1980), S. 2649-2652 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Additional Material: 4 Ill.
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  • 95
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    Journal of Applied Polymer Science 25 (1980), S. 2657-2657 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
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  • 96
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    Journal of Applied Polymer Science 25 (1980), S. 2699-2710 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Moisture-cured polyurethanes were prepared by reacting toluene diisocyanate and sebacic acid-based hydroxy esters such as ethylene glycol sebacate, propylene glycol sebacate, diethylene glycol sebacate, and polyester polyols such as poly(ethylene glycol sebacate), poly(propylene glycol sebacate), poly(diethylene glycol sebacate), and poly(butane diol sebacate). The effect of molecular weight of the esters on film properties and the catalytic effect of 3-5% triethylamine, triethanolamine, and 2-diethylaminoethanol on curing of such films were investigated. Polyurethanes were also prepared using a blend of poly(butane diol carbonate) polyol with polyester polyols. Best polyurethane compositions were obtained when sebacic acid-based polyester polyols were blended with poly(butane diol carbonate) polyol in the ratio of 3:2. These polyurethanes show good tensile strength (120-215 kg/cm2) and elongation (340-460%) properties, having high melting points (247-268°C) and good resistance to solvents and chemicals. Moreover, they are colorless and transparent.
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  • 97
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    Journal of Applied Polymer Science 25 (1980), S. 2285-2294 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A series of C4-C12 alkyl acrylates and methacrylates was polymerized with starch by irradiating starch-monomer mixtures with 60Co. Homopolymers were extracted with cyclohexane. The amounts of insoluble versus soluble synthetic polymer in polymerization run with alkyl acrylates varied less with the chain length of the alkyl substuent than in the polymerizations run with alkyl acrylates varied less with the chain length of the alkyl substituent than in the polymerizations run with alkyl methacrylates; and the poly(alkyl acrylate) contents of cyclohexane-insoluble fractions were all in the 38-45% range. Synthetic polymer contents of the products from butyl, hexyl, and decyl methacrylates were also close to this range. Octyl and lauryl methacrylate, however, gave high conversions to cyclohexane-soluble poly(alkyl methacrylate) along with little or no unextractable synthetic polymer in the starch-containing fractions. Poly(lauryl methacrylate) could be rendered insoluble by incorporating a small amount of tetramethylene glycol dimethacrylate in the polymerization mixture. In a series of polymerizations run with hexyl acrylate and hexyl methacrylate, lower irradiation doses led to more cyclohexane-soluble polymer and less synthetic polymer in the starch-containing fractions. Enzymatic digestion of starch-soluble polymer and less synthetic polymer in the starch-containing fractions. Enzymatic digestion of starch-containing polymers gave synthetic polymer fractions that were largely insoluble in cyclohexane. Crosslinking is, therefore, probably taking place during these polymerizations; however, we could not eliminate the possibility that reduced solubility was caused by small amounts of residual carbohydrate in these polymer fractions. Ceric ammonium nitrate-initiated polymerizations of butyl acrylate, hexyl acrylate, and butyl methacrylate with starch gave cyclohexane-insoluble polymers that contained 33-39% synthetic polymer. The higher alkyl acrylates and methacrylates produced little or no polymer under these conditions. Starch-containing fractions were tested as absorbents for hydrocarbons. Products prepared from decyl acrylate and lauryl acryle acrylate absorbed about 9 g of isooctane per 1 g of polymer, whereas the lowrer alkyl monomers gave polymers with lower absorbency.
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  • 98
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    Journal of Applied Polymer Science 26 (1981), S. 1-8 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Blends of high-density polyethylene (HDPE), polystyrene (PS), and an SEBS triblock copolymer were extruded, pelletized, and injection molded. The binary HDPE-PS blends exhibit very poor ductibility; however, addition of the SEBS block copolymer greatly improves this characteristic but with an accompanying loss in strength and modulus. The modified blends are very tough and have mechanical properties suitable for many end use applications. However, weld lines pose a problem and should be avoided with these blends.
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  • 99
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    Journal of Applied Polymer Science 26 (1981), S. 2391-2401 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The compatibility and phase separation behavior of mixtures of the diglycidyl ether of bisphenol A and carboxyl-terminated butadiene-acrylonitrile copolymers were studied by means of light transmission, viscosity measurements, and optical microscopy. Cloud point measurements of the blends prior to curing showed a strong influence of acrylonitrile on the miscibility behavior, especially near the critical composition of the system. In addition, the cloud point curves showed a highly skewed shape which turned out to be particularly favorable to the formation of a rigid but tough two-phase structure. Blends subjected to isothermal cure at 120°C were found to begin phase separation at a progressively shorter time with increase in the copolymer content. Furthermore, while the phase domains tended to cease growing at the time of gelation, the composition within the sample continued to change well beyond the gel point.
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  • 100
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    Journal of Applied Polymer Science 26 (1981), S. 2423-2436 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A new preparation technique of the polymer plate with high water wettability and sufficient mar resistance was proposed. The gel plate resulting from the prepolymerization of diallyl compound (M1), diallyl phthalate (DAP), in a casting cell was immersed in an aqueous solution of unsaturated carboxylic acid (M2), acrylic acid (AA), and methacrylic acid (MAA), at a specific temperature for a specific time. M2 was copolymerized with the remaining M1 in the region near the surface of the gel plate, and polymer plates with the following characteristics were obtained: for DAP-AA system, θi (contact angle of the alkali-treated plate) = 10.5° and mar resistance (for the alkali-treated plate at a dry state) = 70 g; for DAP-MAA system, θi = 8.3°, and mar resistance = 65 g.
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